Ceramic unit with hollow monolithic ribs



Dec. 8, 1970 F. ASCARI 3,545,156

' CERAMIC UNIT WITH HOLLOW MONDLITHIC RIBS Filed July 5, 1968 INVENTOR M m mm Jim;

ATT RNEY;

United States Patent CERAMIC UNIT WITH HOLLOW MONOLITHIC RIBS Franco Ascari, Via S. Giacomo 7, Carpi, Italy Filed July 5, 1968, Ser. No. 742,620 Claims priority, application Italy, Aug. 11, 1967, 19,422/ 67 Int. Cl. E04c 2/02, 2/38 US. Cl. 52-602 6 Claims ABSTRACT OF THE DISCLOSURE A ceramic panel having stiffening ribs, wherein said panel is of a substantially uniform thickness and said ribs are internally hollow and defined by walls of a substantially uniform thickness and the same as the panel thickness.

This invention relates to a ceramic panel having stiffening ribs, particularly a ceramic panel of a considerable size, and is concerned with a method for obtaining such a panel.

Those skilled in the art are well acquainted with the difficulties being encountered when providing panels and similar articles made of ceramic material, For example, it is well known that, when desiring to obtain a ceramic panel of considerable size, extreme difiiculties will be encountered in handling and moving such a panel from one location to another when the panel is still at a raw state, or very brittle.

In order to provide panels exhibiting a higher mechanical strength at a raw state, attempts have been made to increase the thickness of said panels and to strengthen them by ribs extending on the back face thereof. Such highly thick panels having stiffening ribs would effectively make raw panels more handy, but cause a very serious drawback in that such panels will readily warp or crack on drying and baking; thus, it is well known the extreme difficulty in drying and baking an article of ceramic material when exhibiting substantial thickness differentials from one location to another.

As a result of the foregoing and according to the prior art, when desiring to obtain a large sized panel, said panel has to be divided into a plurality of elemental panels of a small size which are separately dried and baked and then brought together after baking. As evident, this method will substantially raise prime costs for the panel and furthermore will not enable a work of art to retain its full artistic value.

Therefore, it is the main object of the present invention to provide a panel, particularly a large size panel, which can be readily moved at a raw state, dried and baked, correctly retaining the shape imparted thereto on moulding.

It is another object to provide a panel of a relatively low weight and which can be readily manufactured.

Such a panel is characterized by having a substantially uniform thickness and wherein said ribs are internally hollow and defined by walls having a substantially uni form thickness and the same as the panel thickness.

In order that the structure and features of the panel, as well as the method for obtaining such a panel, be more clearly understood, some embodiments thereof will now be described, by mere way of example and not of limitation, reference being made to the accompanying drawing, in which:

FIGS. 1 and 2 are two plan views showing, respectively, the front face and back face of a panel;

FIG. 3 is a cross-section showing a perspective view of a portion of the panel;

FIG. 4 is the cross-section of a die, as shown in a per- Patented Dec. 8, 1970 "Ice spective view, for use for obtaining the panel of FIGS. l3; and

FIG. 5 is a cross-section of a different embodiment of the die, also shown in a perspective view, still for use for obtaining the panel of FIGS. 1-3.

On its front face (FIGS. l-3), the panel as shown in FIGS. l-3 has a fiat front wall 1 surrounded by a shaped and in relief frame 2 entirely extending about the panel and having the configuration of a series of endless steps which extend from the periphery of the front wall 1 to a plane which is spaced beyond the front wall 1. From the back portion of the panel (FIGS. 2 and 3) there project straight longitudinal ribs 3 and straight transverse ribs 4 intersecting ribs 3 at right angles. Still from the back portion of the panel there projects a rib 5 extending throughout the panel periphery.

As apparent from FIG. 3, ribs 3 and 5, as well as ribs 4 intersecting ribs 3 at right angles. Still from the back and the thickness of the walls defining all the ribs is substantially uniform and the same at any location. It will be noted from FIG. 3 that all of the ribs 3 and 5 terminate in end surfaces located in a common plane so that the hollow peripheral rib 5 in the illustrated example has a depth greater than that of the ribs 3 and 4 to terminate in a rear surface which is in the same plane as the rear surfaces of the ribs 3 and 4. Also, it is to be noted that the hollow internal cavities of the longitudinal and transverse ribs 3 and 4 communicate with each other at their intersections While the hollow internal cavities of the ribs 3 and 4 all communicate at their ends with the hollow internal cavity of the peripheral rib 5. Moreover, the interiors of all of the hollow ribs are not visible from the exterior of the panel.

Such a panel, on the front face of which a decorative figure or any other figure can be formed, both in bassrelief and in high-relief, exhibits a high mechanical strength at a raw and baked state, and can be readily dried and baked even at very high temperatures without being subjected to warps, cracks or breakages, and this due to the provision of ribs and to the fact that the thickness of the panel and walls defining the ribs is the same and unifor-m at any location, in spite of this not appearing from an external inspection of the panel. The firing temperatures for the ceramic article are those conventionally used for the particular material used for the panel, this temperature being sufficient to vitrify the clay if it is of a composition which lends itself to the vitrification. Thus, the baking temperature will depend upon the nature of the clay used for the panel. The particular temperature used may be known from past experience with similar materials or can be determined empirically.

As apparent, the panel can be provided on its back face only with longitudinal ribs or transverse ribs, or that the longitudinal ribs can intersect the transverse ribs at angles other than Referring to FIG. 4, a method for obtaining the subject panel will now be described. From the original pattern of the panel, either of a smooth surface or having high-reliefs or bass-reliefs, according to a technique well known to those skilled in the art, a scagliola die or mould base is formed, such a die comprising a bottom wall 6 and side peripheral walls 7: the top surface of wall 6 takes the configuration of the front face for the original panel, whereas side walls 7 correspond to the total thickness of the panel to be formed.

From the die or mould so formed, the original panel is removed and the scagliola making up the mould is allowed to completely dry. The mould so obtained is then filled with barbotine and allowed to dwell therein until a plastic layer of clay has set on the inner mould surfaces, said plastic layer having the same thickness as that of the panel which is desired to be subsequently obtained from the mould, as hereinafter explained. The excess barbotine is caused to flow and the clay which has deposited on the mould walls is allowed to solidify.

It is apparent that the layer of clay, as solidified within the mould, will uniformly follow the whole inner surface of the mould, be it flat or uneven as to the provision of high-reliefs and bass-reliefs. A liquid paste of scagliola is then poured onto this clay so as to form a cover or head mould which, when hardened, is withdrawn from above the mould, from which in turn the solid layer of clay deposited thereon is removed.

On the inner face of the head mould, that is on that face which is designed to face the mould, there are then formed a plurality of grooves parallel or crossed to one another so as to define the plurality of ribs 9 of a substantially trapezoidal cross-section, as clearly seen from FIG. 4.

Head mould 8 is then superimposed to the mould comprising walls 6 and 7, as shown in the sectional view of FIG. 4, and then through holes in the mould and not shown in the figure liquid barbotine is poured into the space between the mould and head mould. The barbotine is allowed to dwell and feed between the mould and head mould for a period which can be experimently determined and which is sufficient for permitting the formation of the thickness for the panel to be formed, and then the amount of liquid excess barbotine is caused to flow. In a manner which is well-known in the art, the excess barbotine may be removed from the interior of the mould through the filling openings, or special drainage openings may be provided. Such openings are plugged until it is desired to drain the excess barbotine from the mould whereupon the plugs of the drainage openings are removed so that the excess barbotine can flow out of the mould. On the free and opposite inner surfaces of the mould and head mould an evenly thick layer of clay is formed, constituting the panel with its internally hollow ribs, as shown in FIG. 5. After a predetermined period the head mould 8 is lifted and the panel removed to be delivered to drying. Thus, the mould and head mould can be reused for forming a new panel, upon drying.

In FIG. there are shown a mould and head mould which can be obtained and used for a modified embodiment of the above method.

According to a technique well known to those skilled in the art, a scagliola mould 10 is formed from an original panel, the upper surface of said mould being the negative correspondence to the front surface of the panel. Two side walls 11 and two end walls 12 are separately prepared, these walls being approachable to the periphery of mould 10, and the inner surface thereof being smooth and such as to enable the mould 10 to move upward or downward relative thereto; the height of walls 11 and 12 will depend upon the thickness of the panel, and ribs fast therewith, which is desired to be obtained by the mould.

Walls 11 and 12 are drawn near the periphery of mould 10 after placing a spacer below said mould 10, the height of the spacer being substantially the same as the thickness of the panel which is desired to be obtained.

Then the top surface of mould 10 is insulated by the thinnest layer as possible of impermeable material and according to an ordinary technique there is poured thereon a layer of scagliola which, after hardening, will form the head mould 13.

On that surface of the head mould designed to face mould 10, straight grooves are formed which when comprising two series of grooves intersecting one another define a plurality of projections 14, as clearly seen in FIG. 5. l

After removing the spacer from below said mould 10, head mould 13 is placed above the mould, so that between said mould, walls 11 and 12 and head mould 13 a closed space is provided, into which barbotine is poured and allowed to dwell and feed in said space for a period which can be experimentally determined, that is until a layer of clay 15 has deposited on the mould and head mould walls, which is then caused to flow through the feeding hole in the walls and not shown in the figure. At a suitable time, head mould 13 is then lifted and the panel removed for delivery to drying.

What I claim is:

1. A ceramic unit having stiffening ribs, wherein said panel consists of a monolithic body having a front panel of substantially uniform thickness and internally hollow ribs defined by walls of a substantially uniform thickness of the same thickness as said front wall, said ribs including substantially straight ribs, one group of which extends perpendicularly to and intersects another group, and a peripheral rib extending throughout the panel periphery and intersected by ends of said groups of straight, intersecting ribs, all of said ribs having hollow internal cavities with the hollow internal cavities of said groups' of ribs communicating with each other at their intersections and the hollow internal cavities of both groups of ribs communicating at the ends of the latter with the hollow internal cavity of said peripheral rib, the cavities being fully enclosed by said panel and rib walls, whereby the hollow interior cavities of all of said ribs are invisible from the exterior of said unit.

2. A panel according to claim 1, all of said ribs having rear surfaces directed away from said front wall and located in a common plane.

3. A panel according to claim 2, said one-piece body including a frame surrounding said front wall and extending therefrom to a plane spaced from said front wall.

4. A panel according to claim 3, said frame being made up of a series of endless steps surrounding said front Wall.

5. A panel according to claim 4, said steps progressing from the periphery of said front wall forwardly away from said rear rib surfaces, and said peripheral rib having a depth greater than the other ribs.

6. A panel according to claim 1, said one-piece body including a relief frame surrounding and extending from said front Wall to a plane spaced from said front wall.

References Cited UNITED STATES PATENTS 1,156,085 10/1915 Kirk 264-269 1,674,763 6/1928 Crispin 264-226 1,778,727 10/1930 Rankin 52-389 2,313,181 3/1943 Thomas v52618 2,324,039 7/1943 Stone 52602 2,858,247 10/1958 Swart 52618 1,503,486 8/1924 Copeman 52-602 2,410,413 11/1946 Hurley 52144 3,392,221 7/ 1968 Kindlesparker et al. 264-86 FOREIGN PATENTS 179,174 1954 Austria 52-630 42,497 1959 Poland 52--602 680,907 10/1952 Great Britain 52602 HENRY C. SUTHERLAND, Primary Examiner US. Cl. X.R. 523l6; 26486 

